Hi K. - This one is long, but I am in the process of writing a book about the common sense of child rearing, so it's near and dear to my heart:
Naturally, of course, my first bit of advice would be to monitor what your child watches on TV... So much of it is inappropriate for children, yet so many still watch it! TIme to sit up and pay attention.
But of course, they grow up, go to school, talk with other kids, etc... and we can't avoid the subject.
I would very much discourage teaching a child her sex education from the television (i.e. DVD's). If you think about it, how is she ever going to learn to discern the truth if her education comes from the TV?? Does that mean that everything she watches on TV is fact? It will if you use it to educate her.
Plus, it makes it such a big production and very unnatural...
The truths is life should come from you. And she should always trust and be free to bring any and every question to you - not her friends or the media.
If you are uncomfortable with that, and you want to use a book, just leave it in her room for her to look at when she wants to. Though I doubt there's much a 7-year old can read herself.
And again, if you sit and read it to her 1) it's a big production that she may not be ready for or in the mood for at that moment, and 2) it's a lot of info at one sitting...
All that said, the Boston Museum of Science has a wonderful human bodies exhibit in which they have a reproduction exhibit - when she is ready, that's a great trip. However, we were there this week and my 10-year old daughter had no interest in it.
With my daughter, the conversation about our bodies and questions about them have had just as easy flow as talking about what we did today. The more natural you can make the conversation, the less impact it will have as something hidden, (i.e. to be kept in the dark - in more ways than one), wrong, dirty, silly, mysterious or whatever.
I hope you have already named our body parts by their correct name, again, just as casually as you would name eyes, knees, elbows, etc. Breats are breasts, not some silly name. Teach her to respect her body. (And when it's time to explore, "private parts, private places" is simple and easy.)
Also, when your child asks you a question, be sure you are very clear on the question before you answer it (you know the joke about the girls who asks her mom where she came from and the mom goes into this whole, long birds and bees explanation and the child just looks at her funny and says - oh. Bobby down the street is from Chicago...)
My daughter asked me three times about mensutration before I asked her if she really wanted to know (more than once, she had asked me what that string was when I got out of the shower...) The third time, I looked her in the eye and asked her if she really wanted to know. She said yes.
So I sat down on the floor of the bathroom and told her - in very simple terms, how our bodies work. It was matter of fact and scientific. She listened, asked a few questions, and that was it. When she was done asking, I was done talking.
So take your cues from your child. Answer just the question asked.
Funny thing was, I felt it was such a profound conversation - and then she promotly forgot it all! Because it wasn't a big deal, and her curiosity was satisfied.
Our children learn who to be in the world from us. So you must show by your example who you want your child to be.
My advice is to clarify and answer questions when they come up, and when topics of concern come up - you do the asking! First of all, where did she see it? (We would like to think it is TV, but what if it isn't? Yikes! Then you might ask one or two of these - who was kissing? How did that make you feel? Do you know why they were kissing? What does kissing mean mean?)
Have fun with it - kids say the darndest things!